Transcript Lecture 31-Herpes Viral Infections2015-04-20 01

Common viral infections
HERPES VIRUS INFECTIONS
• The objectives of this lecture:
 To know the clinically important HVs.
 To know the common characteristics of HVs.
 To know the common modes of transmission of different HVs
 To know the clinical features of these infections, diagnostic
methods and treatment.
HERPES VIRUSES
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Herpes Simplex Virus type1 (HSV-1)
Herpes Simplex Virus type2 (HSV-2)
Varicella Zoster Virus (VZV)
Cytomegalovirus (CMV)
Epstein-Barr Virus (EBV)
Human Herpes Virus 6 (HHS-6)
Human Herpes Virus 7 (HHS-7)
Human Herpes Virus 8 (HHS-8)
HERPES VIRUSES
Characteristics:
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DNA viruses
Encapsulated
Latency after the initial infection
Mostly require close contact for transmission
Human beings are the only reservoir
Virus
Infection
HSV Type 1
Herpes labialis ('cold sores')
Keratoconjunctivitis
Finger infections ('whitlows')
Encephalitis
Primary stomatitis
Genital infections
HSV Type 2
Genital infections
Neonatal infection (acquired during
vaginal delivery)
Varicella zoster virus (VZV)
Chickenpox
Shingles (herpes zoster)
Cytomegalovirus (CMV)
Congenital infection
Disease in immunocompromised patients
Pneumonitis
Retinitis
Enteritis
Mononucleosis like generalized syndrome
Epstein-Barr virus (EBV)
Infectious mononucleosis
Burkitt's lymphoma
Nasopharyngeal carcinoma
Oral hairy leukoplakia (AIDS patients)
Human herpes virus 6
(HHV-6) and 7 (HHV-7)
Exanthem subitum
? Disease in immunocompromised patients
Human herpes virus 8
(HHV-8)
Associated with Kaposi's sarcoma
HERPES VIRUSES
Structure
HERPES VIRUSES
HERPES VIRUSES
• HSV-1 vs HSV-2
Non-genital vs Genital Herpes infection
Primary vs Recurrent infections
Neonatal infection
HERPES VIRUSES
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Transmission by close contact with body secretions
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Exposure to HSV at mucosal surfaces or abraded skin sites permits
entry of the virus and initiation of replication in epidermis and dermis
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After initial infection the virus infects the sensory and autonomic
nerves and become dormant in the ganglion (trigeminal nerve for
HSV1 and sacral root for HSV2)
HSV Gingivostomatitis
Gingivostomatitis and pharyngitis are the most frequent clinical
manifestations of first-episode HSV-1 infection
Herpes Labialis
Recurrent herpes labialis is the most frequent clinical manifestation of
reactivation HSV infection
NON-GENITAL HSV
Genital HSV
Herpetic ulceration of the vulva
Penile herpes simplex (HSV-2) infection
Diagnosis of HSV
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Clinical picture
Viral culture
Cytology
PCR
HSV TREATMENT
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Acyclovir 200 mg five times daily.
Famciclovir 250 mg 8-hourly.
Valaciclovir 500 mg 12-hourly.
The treatment is usually for 5 days
VARICELLA ZOSTER VIRUS
• Primary infection
– Chickenpox
• Recurrent infection
– Herpes zoster
VARICELLA ZOSTER VIRUS
The virus is spread by the respiratory route and replicates in
the nasopharynx or upper respiratory tract.
Followed by localized replication at an undefined site, which
leads to seeding of the reticuloendothelial system and,
ultimately, viremia.
The virus establishes latency within the dorsal root ganglia.
CHICKENPOX
Overall, chickenpox is a disease of childhood, because 90% of
cases occur in children younger than 13 years of age.
VARICELLA ZOSTER
Reactivation of VZV leads to VZ
VARICELLA ZOTER
VARICELLA ZOTER
VZV treatment
• Acyclovir
• Valacyclovir
• Famciclovir
Prevention
VZV vaccination
VZV immunoglobulin (VZIG)
Cytomegalovirus (CMV)
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The largest virus that infects human being
World wide distribution
Latency after primary infection
Infection ranges from asymptomatic to severe
multisystem disease
CMV
Seroepidemiology
Cytomegalovirus (CMV)
Primary infection
• Asymptomatic
• Infectious mononucleosis
Secondary infections in
immunocompromised
patients:
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Pneumonitis
Retinitis
GI such as colitis
Multisystem involvement
CMV Retinitis
Cytomegalovirus (CMV)
Diagnosis:
Diagnosis almost always depends on laboratory
confirmation and
cannot be made on clinical grounds alone.
• Viral cultures from blood ,urine ,tissue
• Serologic tests (antigen detection)
• PCR
Cytomegalovirus (CMV)
TREATMENT:
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ganciclovir
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foscarnet
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cidofovir
Epstein-Barr Virus (EBV)
• Ubiquitous human herpes virus.
• By adulthood 90 to 95% of most populations are positive.
• Spread occurs by intimate contact between susceptible
individuals and asymptomatic shedders of EBV.
• Mostly causes asymptomatic infections.
• Strong association with African Burkitt's lymphoma and
Nasopharyngeal carcinoma.
Epstein-Barr Virus (EBV)
Infectious mononucleosis
Clinical:
• Fever, Sore throat ,Lymphadenopathy
Hematologic:
• >50% mononuclear cells
• >10% atypical lymphocytes
Serologic:
• Transient appearance of heterophile antibodies
• Permanent emergence of antibodies to EBV
Epstein-Barr Virus (EBV)
Diagnosis:
• Heterophile Antibodies are present in about 90%
• Hematologic Findings:
– Lymphocytosis, neutropenia , thrombocytopenia
• EBV specific antibodies
EBV Infection
Atypical Lymphocytes
EBV Infection
Atypical Lymphocytes
EBV Infection
Epstein-Barr Virus (EBV)
Treatment:
Treatment of infectious mononucleosis is largely supportive because
more than 95% of the patients recover uneventfully without specific
therapy
Corticosteroids
• Suggested readings;
• Davidson’s Principles and Practice of Medicine
20th edition
• Kumar & Clark's clinical medicine 7th edition